The Vikings signed free agent offensive tackle Charlie Johnson this morning. Johnson, who played college football at Oklahoma State, was a sixth-round pick by Indianapolis in 2006.

The 27-year-old has played in 73 career games, starting 54 of those. Johnson, 6-4, 305 pounds, appeared in 10 playoff games with the Colts.

He had played left tackle for the Colts -- yes, that is Bryant McKinnie's position -- but reportedly could have been moved to guard had he stayed in Indianapolis.

Johnson started 15 games at left tackle last season and 12 in 2009. In 2008, he started 12 games at left guard and four at left tackle. It will be interesting to see where the Vikings have him working on an offensive line that has some question marks. (Among them is that right guard Anthony Herrera is expected to open camp on the physically unable to perform list.)

The Vikings roster is now at 90 players, the maximum for the opening of training camp.

Matt Vensel is in his first year at the Star Tribune after covering the Ravens for the Baltimore Sun for six years. He is a Pittsburgh native and a Penn State grad. Follow him at @mattvensel.

Mark Craig has covered the NFL for 23 years, and the Vikings since 2003 for the Star Tribune. He is one of 44 Pro Football Hall of Fame selectors. Follow him at @markcraignfl.

Master Tesfatsion is the Star Tribune’s digital Vikings writer. He is a 2013 graduate of Arizona State and worked for mlb.com before arriving in Minneapolis. Follow him at @masterstrib.